Radiation curable ink jet composition and ink jet method

Abstract

A radiation curable ink jet composition includes polymerizable compounds; and a photopolymerization initiator, the polymerizable compounds include a vinyl ether group-containing (meth)acrylate represented by the following general formula (I), a content of the vinyl ether group-containing (meth)acrylate with respect to a total mass of the radiation curable ink jet composition is 15 percent by mass or more, and the photopolymerization initiator includes ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate. H 2 C═CR 1 —CO—OR 2 —O—CH═CH—R 3   (I) In the above formula, R 1 represents a hydrogen atom or a methyl group, R 2 represents a divalent organic residue having 2 to 20 carbon atoms, and R 3 represents a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms.

What is claimed is: 
     
       1. A radiation curable ink jet composition comprising:
 polymerizable compounds; 
 a photopolymerization initiator; 
 2,2,6,6-tetramethylpiperidinyl-1-oxyl or a derivative thereof; and 
 a fluorescent whitener, 
 wherein the fluorescent whitener is at least one selected from the group consisting of a naphthalene benzoxazolyl derivative, a thiophene benzoxazolyl derivative, a stilbene benzoxazolyl derivative, a coumarin derivative, a styrene biphenyl derivative, a pyrazolone derivative, a stilbene derivative, a styryl derivative of benzene and biphenyl, a bis(benzazole-2-yl) derivative, carbostyril, naphthalimide, a derivative of dibenzothiophene-5,5′-dioxide, a pyrene derivative, or pyridotriazole, 
 the polymerizable compounds include a vinyl ether group-containing (meth)acrylate represented by the following general formula (I), 
 a content of the vinyl ether group-containing (meth)acrylate with respect to a total mass of the radiation curable ink jet composition is 15 percent by mass or more, and 
 the photopolymerization initiator includes ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate,
   H 2 C═CR 1 —CO—OR 2 —O—CH═CH—R 3   (I)
 
 
 where in the formula, R 1  represents a hydrogen atom or a methyl group, R 2  represents a divalent organic residue having 2 to 20 carbon atoms, and R 3  represents a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. 
 
     
     
       2. The radiation curable ink jet composition according to  claim 1 ,
 wherein a content of the ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate with respect to the total mass of the radiation curable ink jet composition is 2.0 percent by mass or more. 
 
     
     
       3. The radiation curable ink jet composition according to  claim 1 ,
 wherein the content of the vinyl ether group-containing (meth)acrylate with respect to the total mass of the radiation curable ink jet composition is 50 percent by mass or less. 
 
     
     
       4. The radiation curable ink jet composition according to  claim 1 ,
 wherein the polymerizable compounds include an aromatic-based monofunctional monomer, and 
 a content of the aromatic-based monofunctional monomer with respect to the total mass of the radiation curable ink jet composition is 5.0 to 30 percent by mass. 
 
     
     
       5. The radiation curable ink jet composition according to  claim 1 ,
 wherein the polymerizable compounds include a polyfunctional (meth)acrylate. 
 
     
     
       6. The radiation curable ink jet composition according to  claim 1 ,
 wherein the polymerizable compounds include a urethane acrylate. 
 
     
     
       7. The radiation curable ink jet composition according to  claim 1 ,
 wherein the photopolymerization initiator further includes an acylphosphine oxide-based initiator besides the ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate. 
 
     
     
       8. An ink jet method comprising:
 an ejection step of ejecting the radiation curable ink jet composition according to  claim 1  by a liquid ejection head so as to be adhered to a recording medium; and 
 an emission step of emitting radiation rays to the radiation curable ink jet composition adhered to the recording medium. 
 
     
     
       9. A radiation curable ink jet composition comprising:
 polymerizable compounds; 
 at least one photopolymerization initiator; 
 2,2,6,6-tetramethylpiperidinyl-1-oxyl or a derivative thereof; and 
 a fluorescent whitener, 
 wherein the fluorescent whitener is at least one selected from the group consisting of a naphthalene benzoxazolyl derivative, a thiophene benzoxazolyl derivative, a stilbene benzoxazolyl derivative, a coumarin derivative, a styrene biphenyl derivative, a pyrazolone derivative, a stilbene derivative, a styryl derivative of benzene and biphenyl, a bis(benzazole-2-yl) derivative, carbostyril, naphthalimide, a derivative of dibenzothiophene-5,5′-dioxide, a pyrene derivative, or pyridotriazole, 
 the polymerizable compounds include a vinyl ether group-containing (meth)acrylate represented by the following general formula (I), 
 a content of the vinyl ether group-containing (meth)acrylate with respect to a total mass of the radiation curable ink jet composition is 15 percent by mass or more, and 
 the at least one photopolymerization initiator includes ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate, an amount of the ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate being 30 to 60% by mass relative to a total amount of the at least one photopolymerization initiator contained in the radiation curable ink jet composition,
   H 2 C═CR 1 —CO—OR 2 —O—CH═CH—R 3   (I)
 
 
 where in the formula, R 1  represents a hydrogen atom or a methyl group, R 2  represents a divalent organic residue having 2 to 20 carbon atoms, and R 3  represents a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms.